Start with the Mangekyō and leave Konoha with Madara.

On the snow-covered land, a dusty caravan is heading towards the capital of the Iron Kingdom.

"So you guys are the Chamber of Commerce of Takeo Castle."

In the carriage, Shen Yu sat upright in the corner, talking to the middle-aged man next to him.

"Huh? Haven't you heard of our 'Doudaozhai'?" The middle-aged man looked surprised.

"Sorry, maybe the place where I was born is too remote..." Shen Yu scratched his head and smiled foolishly, "Is it too late to understand now?"

"Okay." The middle-aged man nodded. "Since you are going to live in the capital in the future, it won't hurt for you to know this."

A proud smile spread across his face. "'The Swordsmith' is the largest guild in the entire Iron Country, and the best swordsmith in the world!"

Next, the middle-aged man began to tell his story.

The Land of Iron is a relatively special country in the ninja world. There are no ninja villages or ninjas in this country. Instead, it is a unique country that has derived the profession of "samurai".

It is also because of this that the Iron Country became a neutral country. A long time ago, the ninjas agreed not to take action against this country. In the original time and space, the Iron Country even avoided several Ninja World Wars.

Most of the so-called samurai are swordsmen, which are different from ninjas. They will concentrate the refined chakra on the sword, turning it into sharp sword energy for chopping, and combined with superb swordsmanship, in terms of individual combat capabilities, they are not much worse than ninjas.

Shen Yu nodded frequently after listening to this. The warriors of the Iron Country are unique in their own way, and Madara also speaks highly of their unique swordsmanship.

The quality of a sword, to some extent, determines the strength of a samurai.

Therefore, the profession of knife maker came into being.

The inheritance of swordsmanship has spawned countless schools, and this is even more true for sword-forging. If you want to do your work well, you must first sharpen your tools. Throughout the long course of history, countless famous swordsmiths have emerged. The influence of these people in the ninja world is not worth mentioning, but in the Land of Iron, they play a vital role.

After thousands of years of sedimentation, there are only three knife-making families left that have gathered the essence of the times and combined the strengths of hundreds of families.

They are the "Hyakujuden" of the Iikawa family, the "Giryuden" of the Sugawara family, and the "Isshinden" of the Niwa family.

They have superb skills with a long history and have produced countless famous swords, all of which are national treasures and are collectively known as the "Three Iron Traditions".

One hundred years ago, in order to adapt to the changes of the times, the three families jointly established a Chamber of Commerce. From then on, the three top sword-forging schools merged into one, and "Swordsmith's House" was born.

As a chamber of commerce that houses the top swordsmiths, it took "Dan Dao Zhai" less than ten years to monopolize the entire Iron Kingdom's sword-forging business. It fully undertakes "one-stop" services from the customization and forging of swords to craftsmanship and distribution. As long as there is a demand within the Iron Kingdom, the goods can basically be delivered to the door.

Now this caravan has just completed its delivery mission and is returning to the capital without stopping.

Shen Yu suddenly remembered something and asked casually, "Uncle, since 'Dagger Forging Studio' is so famous, why did the entire caravan only employ two samurai? It shouldn't be too much for a caravan of this size to employ 10 samurai, right?"

“It’s because…” The middle-aged man was suddenly stunned and said hesitantly: “Well…this matter…”

He sighed, "Ah, if it weren't for... our 'Blade Forging House' would be able to flourish for another hundred years without any problem, why would we need to rely on the powerful?"

Shen Yu's eyes moved, "Is there something wrong?"

The middle-aged man's mood was visibly depressed, and he lost interest in talking. He waved his hand and said bitterly, "Forget it. I'm feeling depressed and I'm going to get off the car for a walk. Little brother, the journey home is long, you should conserve your energy and take a rest."

After saying this, he turned around, lifted the car curtain, and walked away with a heavy heart.

Shen Yu blinked his eyes, not feeling disappointed. His passion for gossip was not that strong yet, and besides, he had already chatted enough with other people along the way.

Things like "Swordsmith's Studio" and "Three Legends of Iron" were just idle chats for him to pass the time.

Shen Yu simply crossed his legs, closed his eyes, concentrated, and began to practice.

Soon, his chakra began to mobilize, every cell was like a thawing spring river, intoxicating power flowed through his body, gentle and huge chakra grew from the cells, gurgling and gathering, and wandering in the meridians.

His chakra was like a clear spring, flowing through Lingxu and Shenfeng, and separating into two streams from Tanzhong. One stream flowed from Jiuwei and Juque below into Dantian Qi Hai, and the other stream flowed upward, all of which were immersed in the Yingtang between the eyebrows, and began to circulate along a specific route for the next cycle, repeating over and over again.

Refining chakra is his daily practice, which has never been interrupted for twelve years. The purpose is to open up the meridians, increase chakra reserves, and move forward step by step towards the ambitious goal of "Chatonla".

It's amazing to say, ever since he adapted to the deep sea and optimized himself into the "Body of the Sea God" for the second time, his physical fitness has increased exponentially. This is not only reflected in his powerful strength, speed and defense, but also his chakra volume has skyrocketed.

There seems to be no change on the outside, except that the skin has become more crystal clear and delicate, but inside there is a prehistoric ferocious beast hidden.

If the chakra before was like a trickle, inexhaustible, then now it is like a rushing river, mighty and mighty.

Shen Yu thought about it for a moment and understood the reason.

Chakra is formed by the perfect 1:1 fusion of spiritual energy and physical energy, the combination of yin and yang, which evolves into all things in the universe.

As a descendant of Indra and the owner of the Uchiha clan's Mangekyō Sharingan, his Yin-Tsukushi was already extremely strong. What's more, he also practiced the "Spiritual Transformation Technique", which brought about a qualitative change in his soul and greatly enhanced his mental strength. In comparison, his mediocre physical energy determined the upper limit of his chakra amount.

This is like a wooden barrel filled with water. The shortest piece of wood directly determines the amount of water it can hold.

Now, his physical body has been fully enhanced, and the corresponding physical energy has soared accordingly. The huge spiritual energy has an object to be integrated. The last piece of wood is assembled, and the amount of chakra naturally increases.

It is worth mentioning that when Shen Yu concentrated on refining chakra, his body and soul became one, and his aura was completely restrained. Unless he was a sensing ninja, no one could detect his aura at all.

For Shen Yu who was immersed in cultivation, time passed quickly and it was evening before he knew it.

The snow stopped, but the midnight wind was even more biting, and the cold wind cut the skin like a knife. The middle-aged man could not bear it and returned to the car early. In the long caravan, only two warriors were left outside the car.

The middle-aged man saw Shen Yu resting with his eyes closed in the corner and breathing evenly, so he thought he was asleep and did not disturb him.